If you’re looking forward to lots of outings with your partner, take a look at these details about year-round temperatures in Jieyang: The hottest months are usually July and August, with an average temperature of 27°C, while the coldest months are January and December, with an average of 16°C. The rainiest months in Jieyang are June, August, July and May, with each month seeing an average of 254 mm of rainfall.